“It’s the government understanding that each of the defendants present would apply to plead guilty,” a prosecutor told the judge in the courtroom in New York, where the 10 suspects were appearing together for the first time.

That would be a part of a “plea agreement,” the prosecutor added.

Speculation had been mounting that the suspects would plead guilty under a deal that would see them rapidly leave the United States, with Russia in turn releasing several convicts jailed for spying for the West.

A lawyer for Igor Sutyagin, a Russian arms expert jailed in 2004 on charges of spying for the CIA, said her client may already have been released and taken to Vienna as part of the swap.

Such a swap would allow Russia and the United States to avoid potentially embarrassing and diplomatically damaging court wrangling at a time when they are pursuing a much-vaunted reset of relations.

The 10 were arrested on June 27 in an FBI swoop in Boston and the New York and Washington areas, They are accused of being members of a “deep-cover” spy ring tasked by the Russian secret service with infiltrating US policymaking circles.

All are charged with acting as illegal foreign agents and nine also face the more serious charge of money laundering, which carries a maximum term of 20 years.

An 11th suspect, accused paymaster Christopher Metsos, remains at large after vanishing last week in Cyprus following a court decision to release him on bail.